1. Field of the Invention
The invention relates to methods for processing an emergency call in the IP Multimedia Subsystem (IMS), and more particularly to methods for processing a non-detected emergency call in the IMS.
2. Description of the Related Art
The IP Multimedia Subsystem (IMS) is the technology defined by the Third Generation Partnership Project (3GPP) to provide IP Multimedia services over mobile communications networks. IP Multimedia services provide a dynamic combination of voice, video, messaging, data, etc. within the same session.
The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between user terminals. The Session Description Protocol (SDP), carried by SIP signals, is used to describe and negotiate the media components of the session. Whilst SIP was created as a user-to-user protocol, the IMS allows operators and service providers to control user access to services and to charge users accordingly.
Users of user terminals, for example, may need to make calls in emergency situations. A wireless communications network may identify emergency calls and may route emergency calls to public safety communications systems that may be associated with the wireless communications network.
Users may need to make emergency calls when they are either in a “home” communications network or when the user may be “roaming” and may be proximate to another, “local” or “visited” communications network. However, while the cell phone user is roaming, an emergency call sent from the user's cell phone may not be routed to a public safety system that is associated with the local (or visited) communications network. Thus, the appropriate emergency responders who are located in or near the user's current location may not receive notification in a timely manner.
Therefore, an enhancement method for handling the emergency call in the IP Multimedia Subsystem (IMS) is provided.